Facade seeks to be a minimalist approach to "managing" content. It doesn't try to take over the job of HTML authoring from purpose built desktop authoring systems. However, it will try to manage automatic creation of navigation menus, site search, and other things traditionally automated by traditional content management systems.
It's early days of conceptualisation and development, however Facade is slated to be primarily flat-file based in terms of content. There may be a SQLite component for indexing and site management.
The underlying library behind the XML processing is oriented towards content aggregation (see the sourceforge XAO-PHP project by this author)
The wiki uses Markdown syntax.